Relationship between pathologic T-stage and nodal metastasis after preoperative chemoradiotherapy for locally advanced rectal cancer

Background: We investigated the relationship between pathologic T-stage and mesorectal metastases after preoperative chemoradiotherapy (CRT) for clinical stage II to III rectal carcinoma. Methods: The records of consecutive patients with clinical stage II to III carcinoma of the mid or low rectum who underwent surgery after CRT were reviewed. Indications for preoperative CRT were cancer up to 11 cm from the anal verge, Eastern Cooperative Oncology Group performance status of 0 to 2, age 18 to 75 years, and clinical tumor-node-metastasis stage II or III. Results: The study group consisted of 235 patients (148 men and 87 women; median age, 61 years). The pretreatment tumor-node-metastasis stage was as follows: I, n = 1; II, n = 96; and III, n = 138. Radiotherapy was delivered at a median dose of 50.4 Gy. A pathologic complete response on the rectal wall was found in 24% of patients, and nodal metastases were found in 20% of patients. According to the pT stage, the rate of node positivity was 2% for pT0, 15% for pT1, 17% for pT2, 38% for pT3, and 33% for pT4 cases. At multivariate analysis, the best model for predicting pathologic node involvement included young age, positive pretreatment N status, and pT status. On considering pT stage alone, the odds ratio was in the region of 10 for pT1/2 and >20 for pT3/4 patients. Conclusions: In patients with pT0 after preoperative CRT for clinical stage II to III mid or low rectal cancer, the risk of nodal metastases is very low. More conservative surgery (local excision) may be considered in these cases.